<html>
<head>
<meta http-equiv="content-html" content="text/html;charset=utf-8" />
<title></title>
<script src="http://cdnjs.cloudflare.com/ajax/libs/prefixfree/1.0.7/prefixfree.min.js"></script>
<style>

*{margin:0;padding:0;}
ul,li{list-style:none;}

/* Clearing floats */
.cf:before,
.cf:after {
	content: " ";
	display: table;
}

.cf:after {clear: both;}
.cf {*zoom: 1;}


/* Main level */
.menu {			
	margin: 50px auto;
	width: 800px;
	/* http://www.red-team-design.com/horizontal-centering-using-css-fit-content-value */
	width: -moz-fit-content;
	width: -webkit-fit-content;
	width: fit-content;	
}

.menu > li {
	background: #34495e;
	float: left;
	position: relative;
	transform: skewX(25deg);
}

.menu a {
	display: block;
	color: #fff;
	text-transform: uppercase;
	text-decoration: none;
	font-family: Arial, Helvetica;
	font-size: 14px;
}		

.menu li:hover {
	background: #e74c3c;
}		

.menu > li > a {
	transform: skewX(-25deg);
	padding: 1em 2em;
}

/* Dropdown */
.submenu {
	position: absolute;
	width: 200px;
	left: 50%; margin-left: -100px;
	transform: skewX(-25deg);
	transform-origin: left top;
}

.submenu li {
	background-color: #34495e;
	position: relative;
	overflow: hidden;		
}						

.submenu > li > a {
	padding: 1em 2em;			
}

.submenu > li::after {
	content: '';
	position: absolute;
	top: -125%;
	height: 100%;
	width: 100%;			
	box-shadow: 0 0 50px rgba(0, 0, 0, .9);			
}		

/* Odd stuff */
.submenu > li:nth-child(odd){
	transform: skewX(-25deg) translateX(0);
}

.submenu > li:nth-child(odd) > a {
	transform: skewX(25deg);
}

.submenu > li:nth-child(odd)::after {
	right: -50%;
	transform: skewX(-25deg) rotate(3deg);
}				

/* Even stuff */
.submenu > li:nth-child(even){
	transform: skewX(25deg) translateX(0);
}

.submenu > li:nth-child(even) > a {
	transform: skewX(-25deg);
}

.submenu > li:nth-child(even)::after {
	left: -50%;
	transform: skewX(25deg) rotate(3deg);
}

/* Show dropdown */
.submenu,
.submenu li {
	opacity: 0;
	visibility: hidden;			
}

.submenu li {
	transition: .2s ease transform;
}

.menu > li:hover .submenu,
.menu > li:hover .submenu li {
	opacity: 1;
	visibility: visible;
}		

.menu > li:hover .submenu li:nth-child(even){
	transform: skewX(25deg) translateX(15px);			
}

.menu > li:hover .submenu li:nth-child(odd){
	transform: skewX(-25deg) translateX(-15px);			
}

</style>
</head>
<body>
<ul class="menu cf">
	<li><a href="#">Menu item</a></li>
	<li>
		<a href="#">Menu item</a>
		<ul class="submenu">
			<li><a href="#">Submenu item</a></li>
			<li><a href="#">Submenu item</a></li>
			<li><a href="#">Submenu item</a></li>
			<li><a href="#">Submenu item</a></li>
		</ul>
	</li>
	<li><a href="#">Menu item</a></li>
	<li><a href="#">Menu item</a></li>
	<li><a href="#">Menu item</a></li>

</body>
</html>